Seat backs for vehicular seats

ABSTRACT

A seat back for a vehicular seat has a plate member for supporting a back of a pad and an elastic support mechanism for elastically holding the plate member for moving the plate member in a forward and backward direction with respect to a seat back frame. The plate member includes a first plate portion, a second plate portion positioned on the lower side of the first plate portion, and a third plate portion positioned on the lower side of the second plate portion. The first and third plate portions are more narrow than the second plate portion. The elastic support mechanism includes a rod-shaped elastic bridge member extending horizontally over the seat back frame on the back of the second plate portion. In addition, the elastic bridge member includes a bent portion at the center position as bent along the second plate portion toward the first plate portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a seat back for a vehicular seat.

2. Description of the Related Art

The seat back for the vehicular seat generally includes a seat back frame and a pad. Moreover, the seat back of the type having a thin pad further includes a plate member for supporting the back of the pad, and an elastic support mechanism for holding the plate member elastically and movably forward and backward relative to the seat back frame. The plate member of the prior art is disclosed in U.S. Pat. No. 6,296,308 (308 patent), for example. These plate members are formed into a substantially rectangular shape. And the portion for supporting the lumber of the passenger seated on the vehicular seat is made wider than the remaining portions.

However, there is a need in the art for a plate member and an elastic support mechanism that provides additional support for a user, thus resulting in a more comfortable use.

SUMMARY OF THE INVENTION

One aspect of the present invention can include a seat back for a vehicular seat having a plate member for supporting a back of a pad and an elastic support mechanism for elastically holding the plate member for moving the plate member in a forward and backward with respect to a seat back frame. The plate member includes a first plate portion, a second plate portion positioned on the lower side of the first plate portion, and a third plate portion positioned on the lower side of the second plate portion. The first and third plate portions are more narrow than the second plate portion. The elastic support mechanism includes a rod-shaped elastic bridge member extending horizontally over the seat back frame on the back of the second plate portion. In addition, the elastic bridge member includes a bent portion at the center position as bent along the second plate portion toward the first plate portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a seat for a vehicle;

FIG. 2 is a perspective view of a back of a seat back frame, a plate member and an elastic support mechanism;

FIG. 3 is a perspective view of a back of the plate member;

FIG. 4 is a rear view of the plate member;

FIG. 5 is a cross-sectional view taken along line V-V in FIG. 1; and

FIG. 6 is an enlarged view of a back of an elastic bridge member and a part of the plate member near right side of a bent portion of the elastic bridge member.

DETAILED DESCRIPTION OF THE INVENTION

Each of the additional features and teachings disclosed above and below may be utilized separately or in conjunction with other features and teachings to provide improved seat backs for vehicular seats. Representative examples of the present invention, which examples utilize many of these additional features and teachings both separately and in conjunction with one another, will now be described in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Only the claims define the scope of the claimed invention. Therefore, combinations of features and steps disclosed in the following detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Moreover, various features of the representative examples and the dependent claims may be combined in ways that are not specifically enumerated in order to provide additional useful configurations of the present teachings.

A configuration of the present invention is described with reference to FIGS. 1 to 6. As shown in FIG. 1, a vehicular seat 10 comprises a seat cushion 11 for seating a user, and a seat back 1 for supporting the back of the user. Between the seat cushion 11 and the seat back 1, there are interposed reclining devices 14 for reclining the seat back 1 against the seat cushion 11. A headrest 12 for supporting the head of the user is attached to and is vertically movable in relation to the upper portion of the seat back 1.

As shown in FIG. 1, the seat back 1 can include a seat back frame 2, a pad 7, a plate member 3 for supporting the back side of the pad 7, and an elastic support mechanism 4 for holding the plate member 3 elastically against the seat back frame 2. As shown in FIG. 2, the seat back frame 2 can have a rectangular shape and be composed of left and right side frames 2 a and 2 b, an upper frame 2 c and an under frame 2 d.

The upper frame 2 c is equipped with a pair of cylinder portions 2 e, as shown in FIG. 2. The headrest 12 includes stays 12 a (as referred to FIG. 1) so inserted into the cylinder portions 2 e as can be adjusted in vertical positions. The pad 7 can be formed of an elastically deformable material such as foamed urethane. Moreover, the pad 7 has a predetermined thickness, as shown in FIG. 5, and covers the front side and the side faces of the seat back frame 2. The pad 7 has its surface covered with a surface member 8.

The plate member 3 is made smaller than the seat back frame 2, as shown in FIG. 1, and is arranged on the back side of the pad 7. The plate member 3 is molded of a composite material composed mainly of a resin and glass fibers. The resin may be a polyamide resin such as nylon 6 (PA6). The glass fibers have a weight of 10 to 20 wt. % of the total weight of the composite material. The plate member 3 is formed into a plate shape having a thickness of about 2 mm. As shown in FIG. 3, moreover, the plate member 3 can be defined by plate portions 3 a to 3 e, and by having a left-right symmetric shape.

The first plate portion 3 a is arranged at a height approximately matching or proximate to a scapulae of an adult user, as shown in FIGS. 3 and 4. Moreover, the first plate portion 3 a is shaped on its two transverse sides so as to avoid the scapulae, and therefore it is more narrow than the remaining plate portions 3 b to 3 e. The first plate portion 3 a has a width of 40 to 60% of that of the second plate portions 3 b, for example. The third plate portion 3 c is arranged at a height matching the kidneys of the user. Moreover, the third plate portion 3 c is shaped on its two transverse sides so as to avoid a kidney of a user, and therefore it is more narrow than the second plate portion 3 b. The third plate portion 3 c has a width that is 70 to 90% of a width of the second plate portion 3 b, for example.

The fourth plate portion 3 d is arranged at a height approximately matching or proximate to the lumbar of the user, thus being wider than the remaining plate portions 3 a to 3 c and 3 e. The fourth plate portion 3 d has a width 140 to 160% of a width of the third plate portion 3 c, for example. The fifth plate portion 3 e is arranged at a height approximately matching or proximate to the pelvis of the user, and is tapered to be narrow in a downward direction.

The plate member 3 has a thoracic vertebra avoiding portion 3 f formed at its widthwise center position, as shown in FIGS. 3 and 4. The thoracic vertebra avoiding portion 3 f is formed at such a position of the backbone of the user as corresponds to the thoracic vertebrae, and is vertically elongated from the lower side portion of the first plate portion 3 a to the upper side portion of the fourth plate portion 3 d. The thoracic vertebra avoiding portion 3 f is wider than the thoracic vertebrae, thus having a width of 40 to 100 mm, preferably 50±10 mm. The thoracic vertebra avoiding portion 3 f further defines holes 3 f 1 and 3 f 2 and a recessed portion 3 f 3.

The open holes 3 f 1 and 3 f 2 are defined at the upper and lower positions of the thoracic vertebra avoiding portion 3 f, as shown in FIGS. 3 and 4, and extend through the plate member 3 in the thickness direction. The upper open hole 3 f 1 extends from the lower side portion of the first plate portion 3 a to the general center of the second plate portion 3 b. The lower open hole 3 f 2 extends vertically across the third plate portion 3 c to the upper side portion of the fourth plate portion 3 d.

The recessed portion 3 f 3 is positioned between the open holes 3 f 1 and 3 f 2, as shown in FIGS. 3 and 4. The recessed portion 3 f 3 has slope portions 3 f 6, formed on the two transverse sides, and sloped obliquely backward away from the thoracic vertebrae, and a bottom portion 3 f 7 connecting the slope portions 3 f 6. The recessed portion 3 f 3 has a depth of 5-10 mm, for example. The recessed portion 3 f 3 is so positioned on the lower side of the second plate portion 3 b as to connect the lower left portion and the lower right portion of the second plate portion 3 b. As a result, the recessed portion 3 f 3 prevents the open holes 3 f 1 and 3 f 2 from being largely opened to the left and right when the plate member 3 is deformed.

Moreover, the recessed portion 3 f 3 is positioned, as shown in FIG. 2, between elastic bridge members 5 and 6 of the elastic support mechanism 4. As a result, in case the plate member 3 receives a strong force backward between the elastic bridge members 5 and 6, the open hole 3 f 2 can be prevented from being largely opened to the left and right by the recessed portion 3 f 3. As shown in FIGS. 3 and 4, the recessed portion 3 f 3 is provided with a through hole 3 f 4 and a rib 3 f 5. The through hole 3 f 4 is transversely long, and the rib 3 f 5 is transversely long at the upper side position of the through hole 3 f 4.

As shown in FIGS. 3 and 4, ribs 3 g, 3 h and 3 n are formed on the back of the plate member 3. The rib 3 g is formed on the outer periphery of the upper side of the plate member 3, that is, on the outer peripheral edges of the first to fourth plate portions 3 a to 3 d. The rib 3 h is transversely extended and formed on the back of the fourth plate portion 3 d. As shown in FIG. 2, the lumbar elastic bridge member 6 of the elastic support mechanism 4 is inserted into the ribs 3 h. A gap of 20±10 mm is formed between the ribs 3 h and the open hole 3 f 2 so that the open hole 3 f 2 has no contact with the ribs 3 h. As a result, the plate member 3 rigidity is enhanced, and the concentration of stress is reduced or eliminated in the vicinity of the end portion of the open hole 3 f 2.

The ribs 3 n are vertically extended, as shown in FIG. 4, and formed on the two transverse sides of the thoracic vertebra avoiding portion 3 f. The upper end portions of the ribs 3 n reach the ribs 3 g of the first plate portion 3 a, and the lower end portions extend downward to the ribs 3 h.

The fifth plate portion 3 e has a plurality of openings 3 e 1 formed, as shown in FIGS. 3 and 4. These openings 3 e 1 are made transversely long, and are arranged vertically in plurality. Moreover, the fifth plate portions 3 e has no rib formed on its outer periphery. As a result, the fifth plate portion 3 e is made deformable in the thickness direction and light in weight. A pair of pawls 3 e 2 are formed at the lower end portion of the fifth plate portion 3 e. The pawls 3 e 2 can be hooked on a shaft member 14 a, as shown in FIG. 2. The shaft member 14 a interlocks the left and right reclining devices 14.

As shown in FIG. 2, the elastic support mechanism 4 includes a pair of the elastic bridge members 5 and 6, which are horizontally bridged on the seat back frame 2. The elastic bridge member 5 is an elastic rod-shaped member made of a metal, and is attached to the back of the second plate portion 3 b. The elastic bridge member 5 includes a bent portion 5 a at its center. And horizontal portions 5 b and end portions 5 c are provided on the two sides of the bent portion 5 a.

As shown in FIG. 2, the end portions 5 c are connected to the side frames 2 a and 2 b, and are extended obliquely downward. The horizontal portions 5 b extend substantially horizontally from the end portions 5 c. The bent portion 5 a is bent, as shown in FIG. 6, along the second plate portion 3 b and toward the first plate portion 3 a. The bent portion 5 a has left and right rising portions 5 a 1 and a connecting portion 5 a 2. The rising portions 5 a 1 are extended upward from the horizontal portions 5 b toward the first plate portion 3 a. The connecting portion 5 a 2 extends substantially horizontally, and connects the left and right rising portions 5 a 1.

As a result, the elastic bridge member 5 can elastically support the second plate portion 3 b and movably in a forward and backward direction. Moreover, the elastic bridge member 5 has the bent portion 5 a so that it can support such a force as is applied to the first plate portion 3 a with a torsional force.

On the back of the second plate portion 3 b, as shown in FIGS. 2 and 6, there are formed hook portions 3 j and positioning portions 3 k for holding the elastic bridge member 5. The hook portions 3 j have opening portions 3 j 1, into which the horizontal portions 5 b of the elastic bridge member 5 are inserted from the lower side. The positioning portions 3 k are protruded from the inner sides of the corners of the rising portions 5 a 1 and the connecting portion 5 a 2 of the elastic bridge member 5. As a result, the hook portions 3 j and the positioning portions 3 k regulate vertical movements of the elastic bridge member 5. Moreover, the paired positioning members 3 k regulate transverse movements of the elastic bridge member 5. Thus, the elastic bridge member 5 can be stably held on the plate member 3.

The second plate portion 3 b has erroneous assembly preventing projections 3 m formed on their backs, as shown in FIGS. 2 and 6. The erroneous assembly preventing projections 3 m are formed at the lower side positions of the positioning portions 3 k, thus extending obliquely downward from the positioning portions 3 k. When the elastic bridge member 5 is assembled with the second plate portion 3 b, the erroneous assembly preventing projections 3 m can prevent the bent portion 5 a from coming into the state toward the third plate portion 3 c. Thus, the elastic bridge member 5 can be correctly assembled with the second plate portion 3 b by utilizing the erroneous assembly preventing projections 3 m.

As shown in FIG. 2, the elastic bridge member 5 extends across the left and right ribs 3 n. As a result, the elastic bridge member 5 is positioned backward of the open hole 3 f 1 by a distance at least equal to the height of the ribs 3 n. In case the plate member 3 is elastically deformed, therefore, the elastic bridge member 5 is prevented from pushing the thoracic vertebrae of the user through the open hole 3 f 1.

The elastic bridge member 6 is disposed along the ribs 3 h of the fourth plate portion 3 d, as shown in FIG. 2. The elastic bridge member 6 includes a pair of coil springs 6 a and a wire 6 b, as shown in FIGS. 2 and 5. The ends of the paired coil springs 6 a are connected to the side frames 2 a and 2 b. Moreover, a holding portion 6 d for holding the leading end of the wire 6 b, is attached to the other end portion of one coil spring 6 a. To the other end portion of the other coil spring 6 a, there is attached an outer tube 6 c, into which the wire 6 b is inserted. Moreover, the wire 6 b is tensed between the paired coil springs 6 a.

The wire 6 b and the outer tube 6 c are arranged in the vehicular seat 10, as shown in FIG. 1, and are connected (at one of the end portions) to a take-up portion 13. This take-up portion 13 is mounted on the side portion of the seat cushion 11, and takes up the wire 6 b with respect to the outer tube 6 c, when clockwise turned on its axis, but releases the wire 6 b with respect to the outer tube 6 c when counter-clockwise turned on its axis. As a result, the wire 6 b between the paired coil springs 6 a is adjusted on its length by the take-up portion 13. Therefore, the total length of the lumbar elastic bridge member 6 is adjusted by adjusting the length of the wire 6 b.

Here, the plate member 3 is positionally retained, as shown in FIG. 2, at its upper end portion by the elastic bridge member 5 and at its lower end portion by the pawls 3 e 2. As a result, the plate member 3 is substantially supported at its front and back positions by the elastic bridge member 5 and the pawls 3 e 2. On the other hand, the coil springs 6 a of the lumbar elastic bridge member 6 are attached to the seat back frame 2, thus being positioned on the forward side of the elastic bridge member 5 and the pawls 3 e 2. As a result, the lumbar elastic bridge member 6 can be shortened to push the fourth plate portion 3 d forward. Moreover, the lumbar elastic bridge member 6 can be elongated to move the fourth plate portion 3 d backward. As a result, the elastic bridge member 5 can deform the plate member 3 to adapt the body shape of the user.

In the lumbar elastic bridge member 6 thus adjusted in length, the coil spring 6 a is elastically deformed to move the plate member 3 forward and backward. Moreover, the plate member 3 and the elastic support mechanism 4 are shielded with a protective plate 9 covering the back of the seat back 1, as shown in FIG. 5.

Accordingly, the plate member 3 has the first plate portion 3 a, the second plate portion 3 b and the third plate portion 3 c, of which the first and third plate portions 3 a and 3 c are made narrower than the second plate portion 3 b. The elastic support mechanism 4 has the elastic bridge member 5, and this elastic bridge member 5 has the bent portion 5 a.

In the plate member 3, therefore, the first plate portion 3 a has a small width so that the area for pushing the scapulae is reduced or the plate member 3 doesn't push the scapulae. Moreover, the third plate portion 3 b has a small width so that the area for pushing the vicinity of the kidneys is reduced. As a result, the force to push the vicinities of the scapulae and the kidneys is reduced to improve the comfortableness of the vehicular seat 10. In the plate member 3, moreover, the second plate portion 3 b has a large width, and is supported by the elastic bridge member 5. As a result, the passenger is supported at positions avoiding the vicinities of the scapulae and the kidneys, so that the comfortableness of the vehicular seat 10 is improved. On the other hand, the elastic bridge member 5 is provided at its center position with the bent portion 5 a, which is bent toward the first plate portion 3 a. As a result, the elastic bridge member 5 can support the force applied on the side of the first plate portion 3 a, with its torsional force.

Moreover, the plate member 3 is provided, as shown in FIG. 2, with the fourth plate portion 3 d, which is made wider than the third plate portion 3 c. Moreover, the elastic support mechanism 4 is provided with the lumbar elastic bridge member 6, which is horizontally bridged over or extended between ends of the seat back frame 2, thereby holding or supporting the fourth plate portion 3 d. Therefore, the plate member 3 has the fourth plate portion 3 d, which is made wide and supported by the lumbar elastic bridge member 6. As a result, the lumbar of the passenger can be stably held or supported by the fourth plate portion 3 d and the lumbar elastic bridge member 6. As a result, an improved comfortableness of the vehicular seat 10 can be obtained.

Moreover, the lumbar elastic bridge member 6 can be adjusted in its length, as shown in FIG. 5, so that it can adjust the position of the fourth plate portion 3 d forward and backward. As a result, the fourth plate portion 3 d can be adjusted forward and backward according to the position of the lumbar of the passenger.

While the invention has been described with reference to specific configuration, it will be apparent to those skilled in the art that many alternatives, modifications and variations may be made. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variations that may fall within the spirit and scope of the appended claims. For example, the present invention should not be limited to the representative configuration, but may be modified as described below.

In FIG. 2, the elastic bridge member 5 has the rod shape of a circular section. However, the elastic member may also have a rod shape of a rectangular or polygonal section, or a rod shape of a flat plate.

In FIG. 3, the second plate portion 3 b is provided on its back with the paired hook portions 3 j and the paired positioning portions 3 k. However, the configuration may also be modified to have one of left or right hook portion 3 j and the paired positioning portions 3 k. In this configuration, too, the elastic bridge member 5 can be positioned vertically and transversely.

In FIG. 5, the lumbar elastic bridge member 6 is adjusted in its length to adjust the position of the fourth plate portion 3 d forward and backward. However, another configuration may also be modified into a positionally unadjustable one, in which the lumbar elastic bridge member is identical to the rod-shaped elastic bridge member 5. 

1. A seat back for a vehicular seat comprising: a plate member for supporting a back of a pad; and an elastic support mechanism capable of elastically supporting the plate member for moving the plate member in a forward and backward direction with respect to a seat back frame, wherein the plate member includes a first plate portion positioned to be proximate a scapulae of a user seated on the vehicular seat, a second plate portion positioned on a lower side of the first plate portion, and a third plate portion positioned on a lower side of the second plate portion and positioned to be proximate a kidney of the user, wherein the first and third plate portions are more narrow than the second plate portion, wherein the elastic support mechanism includes a rod-shaped elastic bridge member extending horizontally over the seat back frame on a back of the second plate portion, wherein the elastic bridge member includes a bent portion at a center position, the bent portion being positioned along the second plate portion toward the first plate portion, wherein the rod-shaped elastic bridge member has left and right horizontal portions extending substantially horizontally from left and right end portions of the bent portion, wherein the bent portion has left and right rising portions extended toward the first plate portion from the left and right horizontal portions, and a connecting portion for connecting the left and right rising portions, and wherein the second plate portion has left and right hook portions to be engaged with the horizontal portions, and left and right positioning portions protruded at corners of the rising portions and the connecting portion, so that the elastic bridge member is held by the hook portions and the positioning portions.
 2. The seat back as in claim 1, wherein the back of the second plate portion has an erroneous assembly preventing projection at a lower position of at least one of the positioning portions, and wherein the erroneous assembly preventing projection is capable of preventing the elastic bridge member from being assembled with the second plate portion while the bent portion of the elastic bridge member is directed toward the third plate portion.
 3. A vehicular seat comprising: a seat back including: a frame; a plate member connected to the frame, the plate member including: a first plate portion positioned to be proximate a scapulae of a user, a second plate portion positioned on a lower side of the first plate portion; and a third plate portion positioned on a lower side of the second plate portion and positioned to be proximate a kidney of the user; wherein the first and third plate portions are more narrow than the second plate portion; and an elastic support mechanism capable of elastically supporting the plate member for moving the plate member in a forward and backward direction with respect to the frame, wherein the elastic support mechanism includes a rod-shaped elastic bridge member extending horizontally over the frame on a back of the second plate portion, wherein the elastic bridge member includes a bent portion at a center position, the bent portion being positioned along the second plate portion toward the first plate portion, wherein the rod-shaped elastic bridge member has left and right horizontal portions extending substantially horizontally from left and right end portions of the bent portion, wherein the bent portion has left and right rising portions extended toward the first plate portion from the left and right horizontal portions, and a connecting portion for connecting the left and right rising portions, and wherein the second plate portion has left and right hook portions capable of engagement with the horizontal portions, and left and right positioning portions protruded at the corners of the rising portions and the connecting portion, so that the bridge member is supported by the hook portions and the positioning portions.
 4. The seat back as in claim 3, wherein the back of the second plate portion has an erroneous assembly preventing projection at a lower position of at least one of the positioning portions, and wherein the erroneous assembly preventing projection is capable of preventing the elastic bridge member from being assembled with the second plate portion while the bent portion of the elastic bridge member is directed toward the third plate portion. 